Sense commissioned the survey among deafblind people and their families to mark the start of Deafblind Awareness Week and to celebrate its 50th anniversary.

Although many of the UK's 23,000 deafblind people rely on technology for communication, access to information and achieving independence, the survey reveals a high level of dissatisfaction.

Among the most commonly cited problems, respondents mentioned:

A lack of help when buying items

Information not being available in alternative formats such as audio, large print or Braille

The trend for mobile phones to get smaller

The print size in instruction manuals being too small

"The respondents form a unique group," say the report's authors, Lucy Drescher and Nick Southern.

"As they have both sight and hearing impairments, technology that works well for them will also work well for millions of people with either hearing or sight impairments."

The report finds a complete range of views. One person said that they would be "completely lost" without technology.

Cookers can be dangerous especially if controls are confusing

But another woman, who relies on a ventilator to breathe, accidentally turned off her own air supply when she pressed the button that she thought would summon assistance.

By the time her carer came to check on her, she was unconscious.

Sense says that had the controls been made more accessible she could have avoided a potentially life-threatening situation.

Another potentially fatal incident arose from a lack of consistency in the controls on a gas cooker.

A man who had just bought a new cooker was unaware that the knobs for the two back rings turned clockwise to increase the heat, while the two front rings operated in the reverse direction.

He put some oil in a frying pan on what he thought was a low setting and, while chopping an onion, the pan caught fire because he had in fact turned up the ring to the highest setting.

Helpful advice

Sense says that if products were designed inclusively manufacturers could open up new markets because the technology that works well for people with sight and hearing loss can also be of benefit to anyone with either a sight or a hearing impairment.

As the population ages this is a group that will increase in size.

It says companies can improve their designs by:

Getting advice from deafblind people at the design stage

Using tactile devices like large raised buttons on phones and keyboards

Using large text of colour that contrasts well with the background on buttons and keys

Fitting large screens to devices like mobile phones and allowing the user to customise the text size

Ensuring consistency so that similar types of controls are operated in the same way

Making sure that instruction manuals are written in plain English with large illustrations and in a variety of formats

The charity is also urging the government to take a lead, and to intervene when specialised equipment has a very small market.

And it wants the government to work at European level to ensure that deafblind people are able to buy accessible manufactured goods.